Refining of petroleum oil



?atented Bee. 3G, "i924.

EDGAR M. CLARK, 0 NEW YORK, N. Y., ASSIGNOR '10 STANDARD DEVELOPMENT WM- PANY, A CORPORATION OF DELAWARE.

REFINING or rn'rnonn'ain OIL.

No Drawing.

To all whom it may concern:

Be it known that I, EDGAR M. CLARK, a citizen of the United States, residing at New York, in the county of New York and State of New York, have invented a new and useful Improvement in the Refining of Petroleum Oil, of which the following is a specification.

The present inventionrelates to the art or refining petroleum oil, and will be fully understood from the following specification.

In the ordinary method of refining petroleum oil for the production of marketable products therefrom, it is common to treat the oil with sulphuric acid which is known to have the power of reacting on certain impurities or undesirable constituentsof the oil, notably sulphur compounds present. As the percentage of sulphur in the oil increases, it becomes necessary in general to employ greater quantities of sulphuric acid, with a resultant large increase in the refining loss. l/Vith oil of a poor quality the refining loss involved in an acid treatment adequate for the production of a marketable refined oil may become so high that refining is no longer a profitable operation.

In accordance with the present invention there is provided a new method of refin-- ing by which a marketable product conforming to standard specifications may be produced from an inferior crude oil distillate with a minimum refining cost and loss.

The manner of practisingthe present in vention will be apparent from the following example:

The oil to be refined is a heavy cut produced by rerunning a distillate produced from a Mexican fuel oil by the pyrogenetic decomposition process described in the patent of Wm; M. Burton, No. 1049667 of January 7th, 1913. It has a gravity of 447 B.

and a sulphur content of 477% as determined by the combustion method.

This oil is first treated with 20 pounds per 40 gallon barrel of 66 sulphuric acid as a result of which there is obtained a treated product representing 91.5% of the original oil and having a gravity of 443 B. and a sulphur content of 333%. It will therefore be observed that this first acid Application filed July 3, 1919. Serial No. 308,646.

treatment slightly decreased the Baum gravity and substantially decreases the sulhur content with a refining loss of 8 The product of this first acid treatment is now washed, neutralized and redistilled with fire and steam, and divided into three fractions. The first fraction constituting 28.34% of the treated oil is a heavy naptha having a gravity of 525 B. and a sulphur content of 066%. The second fraction which constitutesthe remainder of the distillate is the kerosene or burning-oil fraction; represents 52% of the treated oil, has a gravity of 44.5 B. and sulphur content of 175%. The third fraction which represents the undistilled residue or bottom amounts to 20% of the treated oil, has a gravity of 34.7 B. and a sulphur content of 1.132%.

With respect to the products obtained by redistilling the treated oil, it will therefore be observed that the sulphur content of both of the distilled fractions is markedly below that of the treated oil while the sulphur content of the undistilled residue or bottom is not only higher than that of the treated oil, but substantially above that of the untreated oil. It'thercfore appears that the effect of the acid treatment is not only to cause the direct elimination in the acid sludge of the sulphur compounds of theoil, but to substantially increase the boiling point of other sulphur compounds which are not actually eliminated by the treating operation, permitting their elimination by a subsequent distillation. That this result is in Iact due to the reaction of the acid is confirmed by the fact that a distillate from the untreated oil having substantially the same gravity, as the bottom of distillation from the treated oil (i. e. 346 as against 343) shows a sulphur content of only .805 as against 1.132, for the bottom from the treated-products. The middle fraction of the treated-.and-redistilled oil produced as above described and having a gravity of 445, sulphur content of .17 5, is new again treated with 20 pounds per 40 gallon barrel of 66 sulphuric acid. As a result of this second treatment there is obtained an oil with a gravity of 44.5 and sulphur content of 10%, and representing 44.72% of the original untreated oil, the refining loss of this second treatment having been 5.44% of the original oil.

The product of the second acid treatment is again redistilled with fire and steam, reducing 90% of distillate and 9.7% of ottoms, or undistilled residue, the distillation loss being 13%. The 90% distillate, representing 40.25% of the orlginal untreated oil,

.585, thus again demonstrating the profound eflect upon the boiling point of the sulphur compounds in the oil resulting from the acid treatment The foregoing represents the nature of the procedure to. he followed in practising the present invention. In general this procedure consists in the division of the treating process into a plurality of steps by which means advantage is taken of the profound modification of the boiling point of the sulphur compounds which are not actually eliminated orthrown down into the sludge by the acid treatment. As a result of this procedure there is a marked economy in the use of acid and in the refining loss as represented bygthe slud e produced. There is necessarily involved t e slight loss resulting from redistillation, but this is quite negligible as compared with treating losses.

In the foregoing example I have given a particular application of the method in which the proportion of acid employed in the two treatments is the same. This is by no means necessary, however, but is to be governed solely by the exigencies of'the particular situation in which the refiner finds himself, as for example, in dealing with an oil of substantially the same characteristics, that is a fraction of a pyrogenetic distillate from Mexican petroleum having a gravity of 456 and a sulphur content of 411%. I may proceed as follows:

The first acid treatment is with 15 pounds per 40 gallon barrel of 66 acid. This ives a refining loss of 3.4% and a treated Oll of gravity 45.7 sulphur 347%. Upon redistillation, as before, there is obtained a naptha fraction of 38.88% of the-treated oil,

gravity 51.8, sulphur .145, and a kerosene fraction representing 41% of the treated oil having a gravity of 449, sulphur conlthe accompanying claims in tent of .244, and a 20% of 364; sulphur .89l.

The kerosene fraction of the treated oil is again .treated, this time with 20 pounds per 40 gallon barrel of 66 acid, giving a refining loss of:8.79%, the treated product bottom of a gravity having a gravity of 462, sulphur content .162. This product of the second treatment the principle and mode of operation of the invention and that I do not regard my invention as limited to the recise processes described, nor to any detai thereof, except in so far as such limitations form a part of which it is my intention to claim all novelty inherent in the invention as broadly as is permissible in view of the prior art.

What I 'claimas new and desire to secure by Letters Patent isi 1. The method of refining petroleum distillates of hi h sulphur content which con,- sists in treatmg'the same with 66 Baum sul huric acid, separating the treated oil, redistilling to leave a botttom of high sulphur concentration, again treating the distillate with 66 Baum sulfuric acid and redistilling as before, whereby there is obtained a 'distillate'of minimum sulphur content with a minimum refining loss.

2. The method-of refining a distillate of Mexican crude petroleum of the class of kerosene or burning oil, havin a high sulphur content of approximate y 0.45%, which consists in treating the same with 66 Baum sulphuric acid and redistilling the treated oil withthe elimination ofa bottom of approximately 20% of high sulphur concentration, again treating the distillate-with 66 Baum sulphuric acid and redistilling the product of the second treatment to eliminate a second bottom of relatively high sulphur content and toproduce-a final-distillate of low sulphur content.

EDGAR MILTON CLARK. 

